.bu{
    display: inline-block;
    line-height: 1;
    white-space: nowrap;
    cursor: pointer;
    background: #FFF;
    border: 1px solid #DCDFE6;
    color: #606266;
    -webkit-appearance: none;
    text-align: center;
    box-sizing: border-box;
    outline: 0;
    margin: 0;
    transition: .1s;
    font-weight: 500;
    padding: 12px 20px;
    font-size: 14px;
    border-radius: 4px;
}
#but{
    color: #409EFF;
    background: #ecf5ff;
    border-color: #b3d8ff;
}

#back{
    /*background: #2577e3;*/
    width: 100%;
    height: 100%;

    background-size:cover;
    /*text-align:center;*/
}
#passage{
    float: left;
    width: 60%;
    /*background: #42b983;*/
    height: 500px;
}
#picture{
    float: left;
    width: 40%;
    /*background: black;*/
    height: 500px;
}
#login{
    top:20%;
    position: absolute;
    background: white;
    width: 420px;
    height: 460px;
    border-radius: 15px;
    border: red;
    box-shadow: 0 4px 6px rgba(0, 0, 0, .2), 0 0 6px rgba(0, 0, 0, .1);
    animation:fadeInDown;
    animation-duration: 0.8s;
}
